No search was conducted on the subject matter of this specification in the U.S. Patent and Trademark Office or in any other search facility.
The vacuum brazing of aluminum heat exchangers is a process well known by skilled artisans. Basically, the aluminum used to form the aluminum heat exchangers is one which has an alloy of aluminum on the surface thereof. When the aluminum alloy is exposed to a vacuum at a relatively high brazing temperature, the surface aluminum flows so that a braze is formed between adjacent aluminum components forming the heat exchanger. In the past, Ford Motor Company has manufactured millions of aluminum heat exchangers used as evaporators for air conditioning systems. Such evaporators are relatively compact heat exchangers.
Ford Motor Company now desires to make vehicle radiators out of aluminum. Such vehicle radiators generally are relatively long in dimensions perpendicular to the direction of airflow therethrough, but relatively thin in dimension with respect to the direction of the airflow therethrough. Thus, the aluminum heat exchangers which are used as radiators in vehicles generally tend to have rather large X and Y dimensions, whereas their Z dimension or depth dimension in the direction of airflow is relatively shallow.
Because of such large dimensions in two directions and a shallow dimension in one direction, difficulty is encountered in manufacturing such heat exchangers in a vacuum brazing operation. Basically, the difficulty is encountered because most of the individual elements making up the assembly are not rigidly bonded to one another prior to the vacuum brazing operation. Thus, the various elements making up the final heat exchanger must be held together carefully prior to the vacuum brazing operation so that the vacuum brazing operation may effect a bonding between the various elements thereof.
Thus, any rack assembly used in the vacuum brazing of aluminum heat exchangers, such as heat exchangers used in automotive vehicles, must be of a design which ensures that prior to the brazing operation the elements making up the aluminum heat exchanger are held in a relatively fixed position and fully supported. Another desirable characteristic for such a rack assembly is that it should be designed so that an aluminum heat exchanger may be both loaded and unloaded rapidly from the rack assembly with a minimum of effort required on the part of the person or persons doing the loading and/or unloading.
The rack assembly of our design is one which accomplishes the desirable objectives set forth above. A first principal objective of the rack assembly of our invention is that any unbrazed aluminum heat exchanger held in our rack assembly is thoroughly supported so that all of the individual elements thereof braze together to form an acceptable finished aluminum heat exchanger. The other principal objective of our rack assembly is that unbrazed heat exchangers may be loaded easily therein and finished brazed aluminum heat exchangers may be removed easily therefrom.